In the textile arts dealing with natural fibers, both at the cotton gin and in the textile mill opening rooms and cotton card licker-in sections, revolving cylinders with surfaces covered with fine, fang-type teeth pluck the fibrous material from a lap or batt of the material which is fed onto the toothed surface of the cylinder by various feed mechanisms. In these conventional systems, the foreign matter is of necessity imbedded in the batt or blanket of the fibrous material, thus, the fang-type teeth of the revolving cylinder must plow through the batt to pluck the fibers from the batt, and in so doing, tend to break up the foreign matter and imbed it in the fiber tufts making separation more difficult. While many of these textile cleaning processes must inherently form the fibrous material into a lap or batt to feed the material onto the fang toothed cylinder, there are some situations in which the method and apparatus of the present invention can avoid the agglomeration of the fibers which entraps the foreign matter between the tufts. In these situations the present invention enhances the foreign matter separation and avoids the breaking up of the foreign matter into finer particles which makes it more difficult to separate from the fibrous material.
One especially propitious situation exists directly following the gin stands in cotton gins. The predominant method of ginning worldwide is the saw gin. It is estimated that the gin saws pull the fibers from a seed in somewhere between ten and thirty fiber tufts. Each tuft then has hundreds of fibers and the trash is located only on the outside of the tufts, and at this point not intimately entangled in the fibers.
The other method of ginning cotton is referred to as the roller gin. In roller ginning, practically all the fibers are stripped from the seed in one large tuft on which the trash is even less entangled on the outer surfaces of the large tufts. In both saw ginning or roller ginning, the trash and fibers as they leave the ginning machine are spaced apart in the most desirable condition for easy separation.
Experiments conducted at the United States Department of Agriculture Ginning Laboratory at Mesilla Park, N. Mex., developed a system of primarily mechanically transferring the tufts of cotton fibers and the commingled trash directly from the doffing brush of the ginning machine to the toothed revolving cylinder of the fiber cleaner. This cylinder is commonly referred to as the lint cleaner saw cylinder. This system of mechanically transferring the lint fibers directly from the doffing brush cylinder of the ginning machine to the lint cleaner saw cylinder is covered in U.S. Pat. Nos. 5,414,900, 5,295,283, and 5,173,994.
Experiences have shown, however, that the apparatus and method covered by these patents have certain shortcomings that our invention overcomes and in addition, our invention results in further improvements in the- cleaning process. The primary shortcoming of the above U.S. patents is that the mechanical transfer of the fibers from the upstream saws to the downstream fiber cleaning saws with doffing brush cylinders cannot be accomplished without some air flow and the U.S. patents attempt to minimize this air flow with the result that the fiber transfer from the doffing brushes to the fiber cleaning saw cylinders is incomplete, thus allowing a certain amount of fiber flow beyond the doffing points. As shown in FIG. 1 of the above U.S. patents, the peripheries of the doffing brush cylinders 2 and 4 are spaced away from the tips of the saw teeth on cleaning cylinders 3 and 5 in an attempt to allow the necessary minimal amount of air to flow past the pinch points as illustrated at 3 on FIG. 1. This narrow space at the pinch points of less than 15 millimeters in practice both greatly reduces the desirable air flow and the efficiency of the fiber transfer from the doffing cylinders to the toothed cleaning cylinders. In practice it was also found that the gin saw cylinders in FIG. 1 are not cleanly doffed due to this reduced air flow around the doffing brush. Also, as described in the U.S. patents, air control bars 11, 17 and 24 must be employed to prevent the recirculation of the incompletely doffed fibers around the doffing brushes because the doffing brushes as at pinch point 3, are spaced away from the tips of the toothed cleaning cylinders to allow the minimum required amount of air to flow there between. As will later be seen, the apparatus and method of our invention overcome these shortcomings.
Referring again to the above U.S. patents drawing FIG. 1, it will be noted that the air laden with dust flows from the gin saws completely through the machine avoiding the cleaning bars 13 and 21 and exits through duct 25 carrying the cleaned fiber thus to recontaminate the fiber with the dust which is very undesirable under some conditions. As will later be seen, at least one of the preferred embodiments of our invention not only removes the dust laden air from the cleaned fiber but does so with larger air volumes providing a dust rinsing action.
Swiftly moving, high volume air streams at the discharge of both saw gins and roller gins normally carry the cotton tufts and trash flowing in spaced apart relationship in the air streams and thus minimize the possibility of agglomeration at these points.
Prior art "saw type" lint cleaners in cotton gins and later textile mill processing remove these conveying air streams by "condensing" the trash and fibers on the slow moving surfaces of condenser drums until the fibers agglomerate into a batt or lap through which the conveying air passes causing the dust to collect in the batt, thus losing the opportunity to more efficiently and more gently separate the trash from the cotton fiber (lint).